Direct alkylation of tin



Patented May 25, 1954 DIRECT ALKYLATION OF TIN Elliott L. Weinberg, LongIsland City, N. Y., as-

' signor to Metal & Th York, N. Y., a corpor No Drawing. Applica SerialNo.

1 Claim.

ing the formula RzSl'lXz where R is a univalent alkyl group, X is ahalogen of the class consisting of chlorine or bromine.

Organotin halides of the type described have been found particularlyuseful in the preparation organic materials such as vinyl chlorideresins, chlorinated paraffins, etc. For example, such organotin halidesmay be employed to make dimethyl tin dilaurate by reaction of the halidewith sodium laurate.

One object of the present invention is to provide a process of producingorganotin halide compound which lends itself to continuous operation,which avoids bomb techniques in which the of a solid contact masscontaining a catalyst of the class consisting of copper, gold and silverto form the compound RzSnXz. More specifically, the organic halide ingaseous or vapor phase is passed through a heated reaction chamcompound.

It has been found in accordance with the present invention, that betteryields are produced with the lower alkyls below butyl. Moreover,

300 C. should be maintained. The solid contact mass should desirablycontain a minimum of 40% by weight of copper. Copper-tin alloys orcompounds containing less than 40% copper do not remain solid at 300 C.The copper-tin con tact mass containing at least 40% copper reermitCorporation, New ation of New Jersey tion April 24, 1951, 222,735

mains solid in the range of elevated temperatures employed.

At reaction temperatures above 400 0., the alkyl halides begin todecompose thermally.

The pressure in the reaction chamber may range from subatmospheric tosuperatmospheric. However, atmospheric pressure in the reaction chamberis preferred.

The process of the present invention is desirably carried out as acontinuous one. The organic halide is passed through the reactionchamber desirably at a rate equal to consumption, 11'

. gas, the flow rate may equal 4 to 5 times the consumption rate.

The effluent gas stream is chilled to condense the organotin halidesproduced. The unreacted organic halide, if any, emerging from thereaction chamber may be recycled or wasted.

The following examples illustrate certain ways mixture of the powderingredients in proper proportions was placed in a Pyrex glass tube. Thetube was placed in a tube furnace and was heated to 300 0. While thetube was heating it was flushed with nitrogen or hydrogen to clear outthe air. Methyl chloride gas was then passed through the tube at a rateof 25 grams per hour. Methyl tin halides were condensed from the outletof the tube within 15 minutes. grams of the product were collected in 3hours. This represented an 84% conversion of methyl chloride to dimethyltin dichloride.

Example 2 A quarter of a pound of CuBSn intermetallic compound powderedto 100 mesh and then briquetted in porous form without a binder wasplaced in a reaction tube as above and was heated to 300-325 C. Afterflushing with nitrogen or hydrogen, methyl chloride gas was passedthrough the tube while at that temperature at a rate of 245 cubiccentimeters per minute. Yields and conversion rates were comparable tothose produced in Example 1.

Example 3 A copper-tin alloy containing 60% by weight of tin and 40 ofcopper in solid particulate form About 160 ranging from -5 mm. to-20mesh in size was present as a particulate porous mass and ofparpacked in the tube in the form of a porous mass. ticle size largerthan 20 mesh, at a temperature After flushing, methyl chloride gas waspassed of about 300 C. and condensing the effluent gas. at a rate of 150cubic centimeters per minute References cited in the m 01 this patentfor 20 hours through the tube heated to 300-325 C. 380 grams of theproduct was collected. This UNITED STATES PATENTS corresponded to 46%conversion for the first pass. Number Name Date Yields comparable toExamples 1 and 2 were ob- 2,444,270 Rochow June 29, 1948 tained byrecycling the gas. 2,625,559 Smith Jan. 13, 1953 What flamed OTHERREFERENCES A process of producing dimethyl tin dichloride, whichcomprises passing methyl chloride in con- Krausei Die Chemie (181'Metal. r an c en tact with a column containing an alloy comprisedVerbindungen, P Edward Brothers of tin and at least 40% copper, saidalloy being Ann Arbor, iMlchlgan (1943)

